China
Africa
Explore chapters and articles related to this topic
X-Nuclei MRI and Energy Metabolism
Published in Guillaume Madelin, X-Nuclei Magnetic Resonance Imaging, 2022
Signal detected:Adenosine triphosphate (ATP): ATP consists of adenosine, composed of an adenine ring and a ribose sugar, and 3 phosphoryl groups called, starting with the group closest to the ribose, α, β and γ . Three ATP peaks can be thus detected: α-ATP, β-ATP and γ-ATP.Phosphocreatine (PCr): PCr is involved in the creatine kinase reaction to produce ATP from ADP.Inorganic phosphate (Pi): Pi is involved in the oxidative phosphorylation process and ATP synthase reaction to produce ATP from ADP.Adenosine diphosphate (ADP): The concentration of ADP is generally too low to be detectable under physiological conditions in vivo, but it can be indirectly calculated from PCr, ATP, and Cr, from the chemical equilibrium of the creatine kinase reaction.Phosphomonoesters (PME): PME phospholipids such as phosphocholine (PC) and phosphoethanolamine (PE) are cell membrane precursors.Phosphodiesters (PDE): PDE phospholipids such as glyc-erophosphocholine (GPC) and glycerol phosphoethanolamine (GPE) are cell membrane degradation products.Phosphatidylcholine (PtdC): PtdC phospholipids are component of biological membrane that can only be detected in the liver.Nicotinamide adenine dinucleotide (NAD): NAD can be detected in its oxidized form NAD+ and reduced form NADH. Both NADH and NAD+ are important factors involved in the mitochondrial processes to produce ATP during oxidative phosphorylation.Uridine diphosphate glucose (UDPGlu): UDPGlu is a nu-cleotide sugar and precursor of glycogen involved in energy metabolism.Uridine diphosphogalactose (UDPGal): UDPGal is involved in nucleotide sugars and energy metabolism.
Dietary supplements for consideration in elite female footballers
Published in European Journal of Sport Science, 2022
Hannah C. Sheridan, Lloyd J. F. Parker, Kelly M. Hammond
Around 60–70% of creatine is stored in skeletal muscle as phosphocreatine. Creatine is available in the diet through the consumption of dairy, red and white meat and fish. In football, creatine is of particular interest due to phosphocreatine stores significantly declining during match play. Thus, with creatine supplementation, repeated sprint performance during both short and prolonged intermittent exercise can be improved. In addition, creatine has been shown to increase post-exercise muscle glycogen resynthesis (Robinson, Sewell, Hultman, & Greenhaff, 1999). Although studies specifically looking at female footballers are sparse and often carried out in sub-elite groups, there has been a consensus that creatine supplementation is beneficial. Female college footballers supplemented with creatine increased strength but not lean tissue during an off-season period (Larson-Meyer et al., 2000). While Cox, Mujika, Tumilty, & Burke (2002) found that creatine improved repeated sprints and agility tasks in a soccer-simulated match play in Australian national team players. Finally, Ramírez-Campillo et al. (2016) discovered that creatine in conjunction with plyometric training enhanced adaptations in amateur female football players.
High-intensity cycling re-warm up within a very short time-frame increases the subsequent intermittent sprint performance
Published in European Journal of Sport Science, 2020
Takuma Yanaoka, Yuka Hamada, Kyoko Fujihira, Ryo Yamamoto, Risa Iwata, Masashi Miyashita, Norikazu Hirose
Another potential mechanism contributing to the increased intermittent cycling sprint performance after both RW trials might be an enhancement of the primary VO2 response after commencement of the CISP. A previous study suggested that there is a close relationship between the ability to maintain intermittent sprint performance and faster VO2 kinetics (Dupont, McCall, Prieur, Millet, & Berthoin, 2010). A reasonable hypothesis (Edholm, Krustrup, & Randers, 2015) that RW may enhance the primary VO2 response to the subsequent exercise was suggested since soccer players started the second half with a higher HR, which is related to VO2 responses during varying non-steady state exercises (Bot & Hollander, 2000), after RW. In the present study, higher VO2 and HR after both RWs were observed, suggesting that the present results supported a previously proposed hypothesis (Edholm et al., 2015), and that an enhanced primary VO2 response may contribute to increased intermittent sprint performance in both RW trials. Moreover, the RW90 trial increased Δoxy-Hb during the CISP, suggesting that oxygen availability in muscle increased after RW. Increased oxygen availability in muscle may accelerate the re-synthesis of phosphocreatine, which is directly related to the ability to perform high-intensity exercise after sprints (Girard et al., 2011; Spencer, Bishop, Dawson, & Goodman, 2005). Therefore, increased oxygen availability in muscle may contribute to the increased intermittent cycling sprint performance after the RW90.
Jump height loss as an indicator of fatigue during sprint training
Published in Journal of Sports Sciences, 2019
Pedro Jiménez-Reyes, Fernando Pareja-Blanco, Víctor Cuadrado-Peñafiel, Manuel Ortega-Becerra, Juan Párraga, Juan José González-Badillo
Sprint ability is a key factor in many sports and is the focus of many training programs (Faude, Koch, & Meyer, 2012; Haugen & Buchheit, 2016). The ability to produce a large forward acceleration with a high maximum running velocity, and to maintain that velocity, contribute to successful performance in a sprint race (Morin et al., 2015; Slawinski et al., 2017). Maximum running velocity in elite sprinters is achieved between 40 and 60 m into the race (Mero, Komi, & Gregor, 1992). This maximal intensity action requires very high energy production in just a few seconds. Metabolic energy is provided mainly by anaerobic glycolysis and phosphocreatine (PCr) metabolism in skeletal muscle cells. Therefore, PCr stores are vitally important in sprint performance, and are severely depleted after 5–7 s of sprinting (Hirvonen, Rehunen, Rusko, & Härkönen, 1987). During a longer distance sprint, such as a 100 m track and field event, anaerobic glycolysis provides the bulk of the adenosine triphosphate (ATP) needed to complete the sprint with minimal impairment of velocity (55–75% of metabolic energy) (Dawson et al., 1997; Hautier et al., 1994; Hirvonen et al., 1987). However, when sprints must be repeated, during competition or training sessions, this may lead to a significant reduction in PCr and ATP concentration and an accumulated loss of adenine nucleotides (Balsom, Seger, Sjödin, & Ekblom, 1992). This large ATP depletion may require a long recovery time and cause impairment in muscle force production (Gorostiaga et al., 2012). In addition, from a metabolic point of view, there are some plausible explanations for fatigue as a result of hydrogen ion (H+) accumulation and increase in inorganic phosphate (Pi) levels (Allen, Lamb, & Westerblad, 2008). Likewise, an increase in blood ammonia level during short-term, high-intensity exercise is usually interpreted as indicative of accelerated ammonia production in muscles, resulting from the deamination of AMP to IMP. The purine nucleotide cycle (PNC) serves, among other functions, to maintain a high ATP/ADP ratio (Hellsten-Westing, Norman, Balsom, & Sjödin, 1993) and acts as an emergency mechanism to prevent muscle ATP from falling to critical levels under conditions of high metabolic stress. Therefore, knowledge of changes in blood lactate and ammonia concentrations during training sessions would provide valuable information about the physiological stress induced.